Richard, The current version doesn’t work with WordPress 4.3. However, I’ve submitted an updated version, which is working on WP 4.3 on several sites and multiple themes. My updated plugin will be called “WP125 Reloaded”, but it will take some time to appear in WordPress (80+ plugins ahead of it for review). In the meantime, you can download it here: http://www.gfwebsoft.com/blog/wp125-reloaded/. It works with all existing WP125 tables and data.

Support:
I’m running a custom version of wp125 on a large client site so, if this is approved by WordPress, I’ll likely provide some degree of support for “wp125 Reloaded” for some time.
I’m also not sure whether wp125 support may resume. I’ve invited the author to integrate any of my fixes into his code. For my uses, wp125 was a great solution!